Adaptive Optics corrected flood imaging of the retina is a well-developed technique. The raw images are usually
of poor contrast because they are dominated by an important background, and because AO correction is only
partial. Interpretation of such images is difficult without an appropriate post-processing, typically background
subtraction and image deconvolution. Deconvolution is difficult because the PSF is not well-known, which calls
for myopic/blind deconvolution, and because the image contains in-focus and out-of-focus information from the
object. In this communication, we tackle the deconvolution problem. We model the 3D imaging by assuming that
the object is approximately the same in all planes within the depth of focus. The 3D model becomes a 2D model
with the global PSF being an unknown linear combination of the PSF for each plane. The problem is to estimate
the coefficients of this combination and the object. We show that the traditional method of joint estimation fails
even for a small number of coefficients. We derive a marginal estimation of unknown hyperparameters (PSF
coefficients, object Power Spectral Density and noise level) followed by a MAP estimation of the object. Such
a marginal estimation has better statistical convergence properties, and allows us to obtain an "unsupervised"
estimate of the object. Results on simulated and experimental data are shown.
Retinal pathologies, like ARMD or glaucoma, need to be early detected, requiring imaging instruments with resolution at
a cellular scale. However, in vivo retinal cells studies and early diagnoses are severely limited by the lack of resolution
on eye-fundus images from classical ophthalmologic instruments. We built a 2D retina imager using Adaptive Optics to
improve lateral resolution. This imager is currently used in clinical environment. We are currently developing a time
domain full-field optical coherence tomograph. The first step was to conceive the images reconstruction algorithms and
validation was realized on non-biological samples. Ex vivo retina are currently being imaged. The final step will consist
in coupling both setups to acquire high resolution retina cross-sections.
We describe here two parts of our future 3D fundus camera coupling Adaptive Optics and full-field Optical Coherence Tomography. The first part is an Adaptive Optics flood imager installed at the Quinze-Vingts Hospital, regularly used on healthy and pathological eyes. A posteriori image reconstruction is performed, increasing the final image quality and field of view. The instrument lateral resolution is better than 2 microns. The second part is a full-field Optical Coherence Tomograph, which has demonstrated capability of performing a simple kind of "4 phases" image reconstruction of non biological samples and ex situ retinas. Final aim is to couple both parts in order to achieve 3D high resolution mapping of in vivo retinas.